Packet Placement for Scalable Video Coding Schemes

ABSTRACT

Methods and systems for pre-conditioning a video stream are provided herein. For example, an apparatus comprising a memory and one or more processors configured to execute instructions stored in the memory are provided. The instructions: identify packets of a first bitstream in a transport stream, such first bitstream corresponding to a base layer; identify packets of a second bitstream in the transport stream, such second bitstream corresponding to an enhancement layer; identify an initial packet corresponding to an ith picture in the first bitstream; identify an initial packet corresponding to the ith picture in the second bitstream; and reorder packets in the transport stream such that the initial packet corresponding to the ith picture in the second bitstream occurs after the initial packet corresponding to the ith picture in the first bitstream.

TECHNICAL FIELD

This disclosure relates in general to processing of video signals, andmore particularly, to provisioning compressed digital video signals tosupport functionality provided by existing video system components withminimal or no changes.

BACKGROUND

Scalable video coding schemes typically include two or more identifiableenhancement video layers that offer visual quality improvements such ashigher picture resolution or the benefits of a high dynamic range (HDR)video signal. The use of scalable video coding schemes, such as when acoded video signal based on two or more packet identifier (PID) flows(or video bitstreams) in an MPEG-2 Transport Stream (“TS”), mayintroduce complexities that hinder functionality provided by existingsystems not originally designed for such schemes. Such issues mayinclude failure in supporting key functionality such as indexing,splicing, and trick mode playback.

Scalable codecs, also known as video coding devices and/or videodecoding devices that support processing of digital video signalsaccording to a Scalable Video Coding (SVC) specification, have attemptedto minimize certain requirements in MPEG-2 Transport Stream, alsoreferred to as MPEG-2 TS. However, such prior approaches have failed toharmonize with existing or previously deployed system components andassume that operations are performed post-arrival of a coded videosignal's data in a coded picture buffer to place operation handling intopart of a buffer model.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a block diagram that illustrates an example environment inwhich video processing (VP) systems and methods may be implemented;

FIG. 2 is a block diagram of an example embodiment of a video signalreceive-and-process (VSRP) device comprising an embodiment of a VPsystem;

FIG. 3 is a flow diagram that illustrates one example method embodimentto process transport packets of a coded video signal; and

FIG. 4 is a flow diagram that illustrates one example method embodimentto process transport packets of a coded video signal.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

Methods and systems for providing and receiving a video coded signal ina transport stream are disclosed. Each successive picture of the codedvideo signal has a first set of packets in the transport streamcorresponding to a base layer and a second set of packets in thetransport stream corresponding to an enhancement layer. Herein, thefirst set of packets is referred to as base layer packets and the secondset of packets as enhancement layer packets. Providing may compriseinputting and processing a first coded video signal to provide a secondcoded video signal that corresponds to a modified version of the firstcoded video signal. Packets of a coded video signal in the transportstream are ordered such that the initial enhancement layer packetcorresponding to an ith picture is provided after the initial base layerpacket corresponding to the ith picture. The packets in the transportstream are further ordered such that the last enhancement layer packetcorresponding to the ith picture is provided before the initial baselayer packet corresponding to an ith+1 picture, wherein the ith+1picture of the coded video signal corresponds to the coded picture indecode order immediately after the ith picture of the coded videosignal. A first minimum delay amount between the initial packet of theith picture in the base layer and the initial packet of the ith picturein the enhancement layer is required to be equal to or greater than aduration for providing a transport stream packet at a piece-wiseconstant bit-rate applicable to an initial packet of the base layer. Asecond minimum delay amount between the last packet of the ith picturein the enhancement layer and the initial packet of the ith+1 picture inthe base layer may be equal to or greater than a duration for providinga transport stream packet at a piece-wise constant bit-rate applicableto a last packet of the enhancement layer.

A minimum delay amount herein may also refer to a minimum time. In oneembodiment, the first minimum delay amount and the second minimum delayamount are equal. In an alternate embodiment, the first minimum delayamount and the second minimum delay amount are different.

In an alternate embodiment, a minimum time is required between the endof the initial base layer packet of the ith picture and the initialenhancement layer packet of the ith picture.

In one embodiment, in accordance with the respective bit rates thatcorrespond to a base layer and an enhancement layer of a coded videosignal, the initial enhancement layer packet in the transport streamcorresponding to the ith picture occurs after a first set of consecutivebase layer packets of the ith picture, where the first set ofconsecutive base layer packets begins with the initial base layer packetof the ith picture and ends with base layer packet immediately prior tothe first occurrence of a base layer packet containing coded pictureinformation of the ith picture. Coded picture information corresponds tothe Video Coding Layer (VCL) information in accordance with the syntaxand semantics of a video coding specification, for example, but notlimited to, such as specified in Recommendation ITU-T H.264 (February2014)/ISO/IEC 14496-10:2014, “Information Technology—Coding of audiovisual objects—Part 10: Advanced Video Coding,” or as specified inRecommendation ITU-T H.265 (October 2014)/ISO/IEC 23008-2:2014—MPEG-HPart 2: High Efficiency Video Coding. The first set of consecutive baselayer packets corresponds to non-VCL information associated or providedwith the ith picture, such as messages or parameters.

A transport stream may be an MPEG-2 Transport Stream as specified inRecommendation ITU-T H.222.0/ISO/IEC 13818-1:2013: “Informationtechnology—Generic Coding of moving pictures and associated audioinformation: Systems.” Herein, a transport packet, such as an MPEG-2Transport Stream packet, may be referred to as a TS packet or a packet.A bitstream corresponding to a coded video signal is transported in anMPEG-2 Transport Stream as an identifiable packetized elementary streamin accordance with the syntax and semantics of the MPEG-2 PacketizedElementary Stream (PES). The MPEG-2 PES packet syntax specifies datafields to properly derive the decoding time stamp (DTS) and presentationtime stamp (PTS) that corresponds to each respective coded picture in aPES. The PES is carried in the payload of MPEG-2 TS packets. A PESpacket may be longer than an MPEG-2 TS packet. Each PES packet ispartitioned and the sequential partitions placed into the payload of thesuccessive TS packets that corresponds to the respective identifiablePES. The packets of a PES are identified by the value of the PID fieldin header of the TS packet. The PID value in the header of an MPEG-2 TSpacket corresponds and identifies a respective PES of the MPEG-2 TS.Each PES in an MPEG-2 TS has a has a unique PID value such that itspackets in the TS can be identified.

The PID value corresponding to a corresponding PES in the MPEG-2 TS isdetermined from information provided in the TS. The MPEG-2 TS includesProgram Specific Information (PSI) that includes the Program AssociationTable (PAT) and the Program Map Table (PMT). Information required toidentify and obtain a sought PMT from the transport stream is providedin the PAT. The PMT contains the PID value associated with each PES ofthe program.

A coded video signal encoded in accordance to a scalable video codingscheme that separates coded picture data, or equivalently the compressedpicture version of a respective picture, into two or more identifiablecoded video layers in an MPEG-2 Transport Stream, such as anidentifiable coded base layer and one or more respectively identifiablecoded enhancement layers. The compressed data of a picture in a codedvideo layer may be referred to as picture or coded picture.

Throughout this specification, the identifiable PES or identifiablebitstream corresponding to a coded base layer in an MPEG-2 TS may bereferred to as the base layer, and the identifiable PES or identifiablebitstream corresponding to an enhancement layer in an MPEG-2 TS may bereferred to as the enhancement layer. The packet of a PES correspondingto a base layer may be referred to as a base layer packet. The packet ofa PES corresponding to an enhancement layer may be referred to as anenhancement layer packet.

The PID value corresponding to a corresponding PES in the MPEG-2 TS isdetermined from information provided in the MPEG-2 TS. The MPEG-2 TSincludes Program Specific Information (PSI) that includes informationfor identifying and obtaining Program Association Table (PAT) andProgram Map Table (PMT). Information. A PMT in the transport stream isidentified by information provided in the PAT. The PMT contains thestream type value and PID value associated for each PES of a respectiveprogram in the MPEG-2 TS. The two respective PID values corresponding toa base layer and an enhancement layer are determined from theinformation provided in the PMT. The PID values are then employed torespectively identify base layer packets and enhancement layer packetsin the MPEG-2 TS.

In one embodiment, a first coded video signal in a transport stream isinput and processed to provide a second coded video signal in thetransport stream that corresponds to a modified version of the firstcoded video signal. Processing of the first coded video signal includesordering the base layer packets and enhancement layer packets thatcorrespond to each of one or more pictures in accordance with a set ofone or more ordering constraints. In an alternate embodiment, anuncompressed video signal is input and processed to provide a codedvideo signal in a transport stream that includes an identifiable baselayer and an identifiable enhancement layer. Processing to provide thecoded video signal includes encoding a video signal in accordance to ascalable coding method to produce a base layer and an enhancement layer,and ordering the base layer packets and enhancement layer packets thatcorrespond to each of one or more pictures in accordance with a set ofone or more ordering constraints. Processing may be performed by a videocompression engine.

In one embodiment, the set of one or more ordering constraintscorresponds to each successive pair of pictures in the coded videosignal, or each successive pair of ith and ith+1 pictures for eachincremental integer value of i. In an alternate embodiment, the set ofone or more ordering constraints is applied only to each instance in thecoded video signal that corresponds to a second type of pictureimmediately following a first type of picture in decode order.

In one embodiment, each picture in the provided or received coded videosignal has corresponding data packets in the Base Layer andcorresponding data packets in the Enhancement Layer.

In an alternate embodiment, each picture in a first subset of picturesof the (provided or received) coded video sequence has correspondingdata packets in the Base Layer and corresponding data packets in theEnhancement Layer, and each picture in a second subset of the picturesof the coded video sequence has corresponding data packets only in theBase Layer. The set of one or more ordering constraints corresponds onlyto the first subset of pictures. The second subset of the pictures maycorrespond to pictures not requiring a benefit or improvement fromcorresponding picture data in the enhancement layer.

In yet a third embodiment, each picture in such second subset ofpictures of the (provided or received) coded video sequence hascorresponding data packets only in the Base Layer for a first portion ofthe coded video signal, and corresponding data packets in both BaseLayer and Enhancement Layer for a second portion of the coded videosignal. The first portion of the coded video signal in the thirdembodiment may correspond to a transmission channel impairment. The setof one or more ordering constraints corresponds only to the firstportion of the coded video signal.

The output order of the pictures in a coded video signal corresponds tothe picture display order according to the picture sequence produced bya camera. The sequence of coded pictures in each layer of the codedvideo signal corresponds to the transmission order or decode order ofthat respective layer. The bitstream in the transport streamcorresponding to a layer of the coded video signal is identifiable by aPID and may be referred to as a PID flow. A PID flow may refer to thesequential processing of an identifiable bitstream, or identifiablepacketized elementary stream in a transport stream that may includeplural multiplexed identifiable packetized elementary streams.

In one embodiment, the first picture Pk in decode order in eachsuccessive set Sk of pictures in a video layer of the coded video signalhas an output time that is after the output time of each of the otherrespective pictures in the that set of pictures. The Pk is an anchorpicture if it is either an intra coded picture or limited to temporalprediction from the immediately preceding anchor picture in decodeorder. In an alternate embodiment, an anchor picture is limited totemporal prediction from the immediately preceding anchor picture andother preceding anchor pictures.

In another embodiment, an anchor picture is the first picture with alater output time after the immediately preceding anchor picture indecode order.

A coded video signal may be referred herein as a stream. A bitstreamcorresponding to a base layer or enhancement layer of the coded videosignal in a transport stream may be referred to as a PID flow.

In another embodiment, an apparatus is provided. The apparatus comprisesa memory and one or more processors configured to execute instructionsstored in the memory. The instructions include: identifying packets of afirst bitstream in a transport stream, such first bitstreamcorresponding to a base layer; identifying packets of a second bitstreamin the transport stream, such second bitstream corresponding to anenhancement layer; identifying an initial packet corresponding to an ithpicture in the first bitstream; identifying an initial packetcorresponding to the ith picture in the second bitstream; and reorderingpackets in the transport stream such that the initial packetcorresponding to the ith picture in the second bitstream occurs afterthe initial packet corresponding to the ith picture in the firstbitstream.

In another embodiment, a method is provided. The method identifiespackets of a first bitstream in a transport stream, such first bitstreamcorresponding to a base layer; identifies packets of a second bitstreamin the transport stream, such second bitstream corresponding to anenhancement layer; identifies an initial packet corresponding to an ithpicture in the first bitstream; identifies an initial packetcorresponding to the ith picture in the second bitstream; and reorderspackets in the transport stream such that the initial packetcorresponding to the ith picture in the second bitstream occurs afterthe initial packet corresponding to the ith picture in the firstbitstream.

In another embodiment, a method is provided of encoding a sequence ofuncompressed pictures into a coded video signal in transport stream(“TS”) bitstream that includes a first bitstream and a second bitstream.The method includes receiving a sequence of uncompressed picturesincluding a first picture; and processing the first picture into a codedpicture comprising a first sequence of packets in the first bitstreamand a second sequence of packets in the second bitstream, such that theinitial packet of first picture in the second bitstream is after theinitial packet of first picture in the first bitstream. This method maybe implemented by a processor or a plurality of processors coupled tomemory.

Example Embodiments

Embodiments of the present disclosure generate a coded video signal suchthat operations on the base layer of the coded video signal implicitlyoperate on any or all of the enhancement layers. For example, a codedvideo signal may contain a base layer with pictures B1, B2, . . . , Bi,. . . Bn in a particular transmission order or decode order. The codedvideo signal may also contain one or more enhancement layers withpictures Sx1, Sx2, . . . , Sxi, . . . Sxn (where x is the layer). Forexample, in some embodiments, a value of 1 for x may indicate a singleenhancement layer. Although the method of providing or receiving thecoded video signal is described with respect to a single enhancementlayer, the method may be extended to multiple enhancement layers,irrespective of the type of dependencies or interdependencies, or lackthereof, between or among the base layer and the additional enhancementlayers, or between the enhancement layers themselves. In one embodiment,pictures Sx1, Sx2, . . . , Sxi, . . . Sxn refer to correspondingenhancement information for each of the respective pictures, B1, B2, . .. , Bi, . . . Bn, of the base layer. In a second embodiment, picturesSx1, Sx2, . . . , Sxi, . . . Sxn refer to pictures of an enhancementlayer corresponding to temporal scalability, where each picture in theenhancement layer corresponds to a picture with an output time betweenthe respective output time of two pictures of the base layer.

Piece-wise constant bit rate (CBR) may represent a constant bitratecalculated between two Program Clock Reference (PCR) values for aprogram over a given PID flow.

In an alternate embodiment, a coded video signal's base layer packetsand enhancement layer packets are required to comply to a set of one ormore ordering constraints, in the transport stream only where twoconsecutive pictures, in decode order, respectively correspond to afirst type of picture and a second type of picture. Ordering base layerpackets and enhancement layer packets for any other pair of consecutivepictures in the coded video signal is unnecessary and not performed.Ordering of the base and enhancement layer packets is provided at eachinstance in the coded video signal where the first type of picture isimmediately followed (in decode order) by the second type of picture. Ateach such instance in the transport stream, the packets are ordered suchthat the last enhancement layer packet of the first type of picture(i.e., the ith picture) is provided before the initial base layer packetof the second type of picture (i.e., the ith+1 picture). The packets ofthe transport stream are further ordered such that the first enhancementlayer packet of the second type of picture is provided after the firstbase layer packet of the second type of picture. A first base layerpacket of a picture corresponds to the initial packet in the base layerthat corresponds to that picture, also referred to as the initial baselayer packet. Similarly, a first enhancement layer packet of a picturecorresponds to the initial packet in the enhancement layer thatcorresponds to that picture, also referred to as the initial enhancementlayer packet.

In one embodiment, the first type of picture corresponds to the pictureimmediately prior to a Random Access Point (RAP) picture, and the secondtype of picture corresponds to the RAP picture, thus facilitatingfunctionality extended by existing system components, such as randomaccess such as when changing to another TV channel, Digital ProgramInsertion (DPI) functionality or commercial or advert insertion. The RAPpicture is an intra coded picture. A RAP corresponds to a point of thecoded video signal where a decoder can start decoding without dependenceon any prior portion of the coded video signal. A RAP picture is alwaysan anchor picture.

A RAP picture may corresponds to an Out-Point or In-Point thatfacilitates DPI functionality. An Out-Point corresponds to a RAP picturewith a PTS value equal or substantially equal to the PTS value providedin a message in the transport stream, such message identified ascorresponding to an Out-Point and provided in the transport stream priorto the start of the RAP picture. In one embodiment, the second type ofpicture may correspond to an Out-Point for the start of programinsertion. In another embodiment the second type of picture maycorrespond to an In-Point that ends an inserted program. The In-Pointcorresponds to a RAP picture with a PTS value equal or substantiallyequal to the PTS value provided in a message in the transport stream,such message identified as corresponding to an In-Point and provided inthe transport stream prior to the start of the RAP picture. In yetanother embodiment, the second type of picture may correspond to a RAPpicture corresponding to an Out-Point or an In-Point.

In another embodiment, the first type of picture corresponds to thepicture immediately prior to an anchor picture, and the second type ofpicture corresponds to the anchor picture, thus facilitating trick modefunctionality in existing system components as well as DPI. Trick modesrefer to video playback modes that differ from the normal video playbackmode, either in speed or in direction. Directions are either reverse orforward as in normal video playback mode. Speed may differ when theplayback mode is faster or slower than the speed of the normal videoplayback mode. Slower speeds include slow playback or frame stepping, aswell as pause which is a speed of zero.

In one embodiment, trick modes with a speed faster than the speed of thenormal playback mode are realized in a video decoder by only decodingbase layer pictures whereas trick modes with a speed slower than thespeed of the normal playback mode are realized with pictures that areeach derived from a respectively corresponding decoded base layerpicture and a respectively corresponding decoded enhancement layerpicture.

Throughout the present disclosure, the term “tier” corresponding to arespective picture represents its dependency level on previous picturesin the coded video signal. Previous pictures refers to the picturedecode order such as the decode order of pictures in the base layer ofthe coded video signal. Previous pictures may serve as referencepictures, or more generally, pictures required to be decoded for theproper decoding of a picture. A picture with tier value equal to k, Pk,can be properly decoded if each picture with a respectivelycorresponding tier value equal to or less than k is decoded when thevideo decoding operation starts earlier or at the preceding RAP in thebitstream closest to picture Pk. An I-frame, or intra coded picture mayhave the lowest tier value, such as tier value equal to 0 or 1, as it isnot dependent upon other frames. A RAP picture has the lowest tiervalue. A picture with a corresponding tier value is not dependent uponany other picture in the coded video signal with a larger tier value. Asecond picture that uses a first picture as a reference picture, suchfirst picture having a corresponding tier value equal to k, may have acorresponding tier value equal to k+1. For example, a picture using areference picture with a tier value equal to 1 may have a correspondingtier value equal to 1 or higher. Alternatively, A second picture thatuses a first picture as a reference picture, such first picture having acorresponding tier value equal to k, may have a corresponding tier valueequal to k or higher.

In one embodiment, ordering of the base and enhancement layer packets isprovided at each instance in the coded video signal where the first typeof picture is immediately followed (in decode order) by the second typeof picture, and the second type of picture corresponds to a picture witha corresponding tier value equal to k. This embodiment may provisiontrick modes with a certain level of quality. This embodiment may alsoprovision graceful transitions between the base and enhancement layers.

In one embodiment, each base layer picture has a corresponding tiervalue. In another embodiment, each base layer picture has acorresponding tier value and each enhancement layer picture has acorresponding tier value. According to embodiments of the presentdisclosure, the initial packet of picture Sxi may occur after theinitial packet of picture Bi. The amount of delay between the respectiveinitial packets of picture Bi and picture Sxi may be at a minimum of theduration of a TS packet (1504 bits) at the piecewise CBR applicable tothe initial packet of the base layer. Furthermore, the amount of delaybetween the respective initial packets of picture Bi and picture Sxi maybe at the duration of more than one TS packet. In an alternateembodiment, the duration is a minimum number of TS packets.

The last packet of picture Sxi may occur before the initial packet ofpicture Bi+1. The time or amount of delay between the last packet ofpicture Sxi and the initial packet of picture Bi may be at a minimum ofthe duration of a transport stream (TS) packet at the piece-wise CBRapplicable to the last packet of the enhancement layer Sxi. Furthermore,the time or amount of delay between the last packet of picture Sxi andthe initial packet of picture Bi+1 may be at a duration of more than oneTS packet. In an alternate embodiment, the duration is a minimum numberof TS packets.

According to embodiments of the present disclosure, the processing of acoded video signal provides a PTS for each picture Sxi that is the sameas, substantially equal to, or a value indicating equivalence to, thePTS of the respectively corresponding enhancement layer picture Bi. Forexample, substantially equal to may comprise, but is not limited to, avalue that is plus or minus 5% of the value inclusively. Similarly, theDTS of picture Sxi may be the same as, substantially equal to or less,or a value indicating equivalence to, the DTS of the respectivelycorresponding enhancement layer picture Bi. In some embodiments, theencoding process provides the tier value of Sxi to be greater than orequal to the tier of Bi.

These constraints above are described in the context of between a baselayer and an enhancement layer. However, embodiments of the presentdisclosure may be applicable to between one enhancement layer and adependent enhancement layer. By defining the ordering and propertiesthat are required of a scalable coding scheme, embodiments of thepresent disclosure may allow much infrastructure to be re-used withoutbeing aware of scalable coding schemes.

A coded video signal with at least one enhancement layer correspondingto a scalable element or elements may require processing to modify theorder of the base layer and enhancement layer packets to avoid a rangeof complex processing operations not supported by existing systemequipment. Embodiments of the present disclosure may simplify oreliminate the implementation of such complex processing operations, suchas to provision splicing and trick mode functionality of coded videosignals. Embodiments may avoid the need for certain components todemultiplex, decode and/or re-multiplex a scalable coded video signalprovided as a multiplex of identifiable elementary streams in atransport stream.

FIG. 1 is a high-level block diagram depicting an example environment inwhich one or more embodiments of a video processing (VP) system may beimplemented. In particular, FIG. 1 is a block diagram that depicts anexample subscriber television system (STS) 100. In this example, the STS100 includes a headend 110 and one or more video signalreceive-and-process (VSRP) devices 200. In some embodiments, one of theVSRP devices 200 may be equipped with functionality to process tiervalue information that affects proper trick mode functionality.

According to embodiments of the present disclosure, a receiver, such asVSRP devices 200 and the headend 110 are coupled via a network 130. Theheadend 110 and the VSRP devices 200 cooperate to provide a user withtelevision services, including, for example, broadcast televisionprogramming, interactive program guide (IPG) services, VOD services, PVRservices, DVR services, and pay-per-view, as well as other digitalservices such as music, Internet access, commerce (e.g., home-shopping),voice-over-IP (VOIP), and/or other telephone or data services.

The VSRP device 200 is typically situated at a user's residence or placeof business and may be a stand-alone unit or integrated into anotherdevice such as, for example, the display device 140, a personalcomputer, personal digital assistant (PDA), mobile phone, among otherdevices. In other words, the VSRP device 200 (also referred to herein asa digital receiver or processing device or digital home communicationsterminal (DHCT)) may comprise one of many devices or a combination ofdevices, such as a set-top box, television with communicationcapabilities, cellular phone, personal digital assistant (PDA), or othercomputer or computer-based device or system, such as a laptop, personalcomputer, DVD/CD recorder, among others. As set forth above, the VSRPdevice 200 may be coupled to the display device 140 (e.g., computermonitor, television set, etc.), or in some embodiments, may comprise anintegrated display (with or without an integrated audio component).

The VSRP device 200 receives signals (video, audio and/or other data)including, for example, digital video signals in a compressedrepresentation of a digitized video signal, referred also as a codedvideo signal, from the headend 110 through the network 130, and providesreverse information to the headend 110 through the network 130.

Television services may be presented via respective display devices 140,each of which typically may include a television set. However, thedisplay devices 140 may also be any other device capable of displayingthe sequence of pictures of a video signal or derived from a coded videosignal including, for example, a computer monitor, a mobile phone, gamedevice, etc. In one implementation, the display device 140 is configuredwith an audio component (e.g., speakers), whereas in someimplementations, audio functionality may be provided by a device that isseparate yet communicatively coupled to the display device 140 and/orVSRP device 200. Although shown communicating with a display device 140,the VSRP device 200 may communicate with other devices that receive,store, and/or process coded video signals from the VSRP device 200, orthat provide or transmit coded video signals or uncompressed videosignals to the VSRP device 200.

The network 130 may comprise a single network, or a combination ofnetworks (e.g., local and/or wide area networks). Further, thecommunications medium of the network 130 may comprise a wired connectionor wireless connection (e.g., satellite, terrestrial, wireless LAN,etc.), or a combination of both. In the case of wired implementations,the network 130 may comprise a hybrid-fiber coaxial (HFC) medium,coaxial, optical, twisted pair, etc. Other networks are contemplated tobe within the scope of the disclosure, including networks that usepackets incorporated with and/or are compliant to MPEG-2 Transport withHEVC coding or other transport layers or coding protocols.

The headend 110 may include one or more server devices (not shown) forproviding coded video signals, audio, and other types of media or datato client devices such as, for example, the VSRP device 200. The headend110 may receive content from sources external to the headend 110 or STS100 via a wired and/or wireless connection (e.g., satellite orterrestrial network), such as from content providers, and in someembodiments, may receive package-selected national or regional contentwith local programming (e.g., including local advertising) for deliveryto subscribers. The headend 110 may also include one or more encoders(encoding devices or compression engines) 111 (one shown) and one ormore video processing devices embodied as one or more splicers 112 (oneshown) coupled to the encoder 111. In some embodiments, the encoder 111and splicer 112 may be co-located in the same device and/or in the samelocale (e.g., both in the headend 110 or elsewhere), while in someembodiments, the encoder 111 and splicer 112 may be distributed amongdifferent locations within the STS 100. For instance, though shownresiding at the headend 110, the encoder 111 and/or splicer 112 mayreside in some embodiments at other locations such as a hub or node. Theencoder 111 and splicer 112 are coupled with suitable signaling orprovisioned to respond to signaling for portions of a coded video signalcorresponding to a video service or video program where commercials areto be inserted.

The STS 100 may comprise an IPTV network, a cable television network, asatellite television network, a cellular network, a subscriber network,or a combination of two or more of these networks or other networks.Further, network PVR and switched digital video are also consideredwithin the scope of the disclosure. Although described in the context ofvideo processing, it should be understood that certain embodiments ofthe VP systems described herein also include functionality for theprocessing of other media content such as coded audio signals orcompressed audio streams.

The STS 100 comprises additional components and/or facilities not shown.For instance, the STS 100 may comprise one or more additional servers(Internet Service Provider (ISP) facility servers, private servers,on-demand servers, channel change servers, multi-media messagingservers, program guide servers), modulators (e.g., QAM, QPSK, etc.),routers, bridges, gateways, multiplexers, transmitters, and/or switches(e.g., at the network edge, among other locations) that process anddeliver and/or forward (e.g., route) various digital services tosubscribers.

In one embodiment, the VP system includes the headend 110 and one ormore of the VSRP devices 200. In some embodiments, the VP systemincludes portions of each of these components, or in some embodiments,one of these components or a subset thereof. In some embodiments, one ormore additional components described above yet not shown in FIG. 1 maybe incorporated in a VP system.

FIG. 2 is an example embodiment of select components of a VSRP device200. The VSRP device 200 shown in FIG. 2 is merely illustrative, andshould not be construed as implying any limitations upon the scope ofthe disclosure. In one embodiment, a VP system may include allcomponents shown in, or described in association with, the VSRP device200 of FIG. 2. In some embodiments, a VP system may include fewercomponents, such as those limited to facilitating and implementing theproviding, processing, or decoding of a coded video signal and/or outputpictures corresponding to decoded versions of coded pictures in thecoded video signal, where such coding pictures is according to ascalable video scheme and such coded video signals includes a base layerand an enhancement layer. In some embodiments, functionality of the VPsystem may be distributed among the VSRP device 200 and one or moreadditional devices as mentioned above.

The VSRP device 200 includes a communication interface 202 (e.g.,depending on the implementation, suitable for coupling to the Internet,a coaxial cable network, an HFC network, satellite network, terrestrialnetwork, cellular network, etc.) coupled in one embodiment to afront-end-processing component such as a tuner system 203. The tunersystem 203 may include one or more tuners for receiving downloaded (ortransmitted) media content. The tuner system 203 or front-end-processingcomponent can be controlled to select from a plurality of transmissionsignals provided by the STS 100 (FIG. 1). The tuner system 203 orfront-end-processing component enables the VSRP device 200 to receivedownstream media and data transmissions, thereby allowing a user toreceive digital media content via the STS 100. The tuner system 203includes, in one implementation, an out-of-band tuner for bi-directionaldata communication and one or more tuners (in-band) for receivingtelevision signals. In some embodiments (e.g., IPTV-configured VSRPdevices), the tuner system may be omitted.

The tuner system 203 or front-end-processing component may be coupled toa demultiplexing/demodulation system 204 (herein, simply demux 204 forbrevity). The demux 204 may include MPEG-2 Transport demultiplexingcapabilities. When tuned to carrier frequencies carrying a digitaltransmission signal, the demux 204 enables the separation of packets ofdata, corresponding to the identifiable bitstreams of the selected ordesired video service or video program, for further processing.Concurrently, a PID filtering component in the demux 204 precludesfurther processing of packets in the multiplexed transport stream thatare irrelevant or not desired, such as packets of data corresponding toother video services or video programs. Parsing capabilities of thedemux 204 allow for the ingesting by the VSRP device 200 of programassociated information carried in the transport stream and/or codedvideo signal. The demux 204 is configured to identify and extractidentified information in one or more bitstreams, such as assistanceinformation, to facilitate the identification, extraction, andprocessing of the coded pictures. Such assistance information maycorrespond to a RAP, the tier value corresponding to each respectivecoded picture of a coded video signal, the start or initial transportpacket of each respective picture in the bitstream corresponding to thebase layer of the coded video signal, and the start or initial transportpacket of each respective picture in the bitstream corresponding to theenhancement layer of the coded video signal. The last packet of arespective picture in a bitstream may be identified as the last packetprior to the initial packet corresponding to the next picture in thatbitstream. Other such information includes Program Specific Information(PSI) (e.g., Program Map Table (PMT), Program Association Table (PAT),etc.) and parameters or syntactic elements (e.g., Program ClockReference (PCR), time stamp information, payload_unit_start_indicator,etc.) of the transport stream (including packetized elementary stream(PES) packet information).

The initial base layer TS packet corresponding to a picture of anidentifiable base layer bitstream may be signaled with a first auxiliaryinformation in the transport stream, such as by setting thepayload_unit_start_indicator bit to a value equal to “1” in the headerof the MPEG-2 TS packet corresponding to the initial base layer TSpacket of the picture. The initial base layer TS packet corresponding toa picture of an identifiable enhancement layer bitstream may be signaledsimilarly with the first auxiliary information in the transport stream,such as by setting the payload_unit_start_indicator bit to a value equalto “1” in the header of the MPEG-2 TS packet corresponding to theinitial enhancement layer TS packet of the picture. A system componentor VSRP 200 may determine the initial TS packet corresponding to apicture of an identifiable bitstream from the signaled first auxiliaryinformation.

The start of a RAP picture, or initial packet of the RAP picture, may besignaled with a second auxiliary information in the transport stream,such as by setting equal to “1” the random_access_indicator and/orelementary_stream_priority_indicator in the Adaptation Field of the TSpacket corresponding to the initial TS packet of the RAP picture. Asystem component or VSRP 200 may determine the initial TS packetcorresponding to a RAP picture of an identifiable bitstream from thesignaled second auxiliary information, such as therandom_access_indicator and/or elementary_stream_priority_indicator.

By signaling both the first auxiliary information and the secondauxiliary information for the initial packet of a RAP picture theinitial packet corresponding to the RAP picture is differentiated fromthe initial packet of a picture that is not a RAP picture. A systemcomponent or VSRP 200 may differentiate the initial TS packetcorresponding to a RAP picture from the initial TS packet correspondingto a picture that is not a RAP picture from the second auxiliaryinformation and the first auxiliary information.

In one embodiment, a system component located in headend 111 orelsewhere in network 130 includes all or a portion of the processingcomponents in VSRP 200 to effect to modify a coded video signal byordering the base layer and enhancement layer packets of the coded videosignal.

In one embodiment, additional information extracted by the demux 204includes the aforementioned assistance information pertaining to thepictures of the coded video signal that assists the decoding logic (incooperation with the processor 216 executing code of the VP logic 228)to affect certain behavior to provide operations, such as requestedtrick modes, wherein the assistance information pertains to pictureinterdependencies related by successive tier numbers, and in someembodiments, further assists display and output logic 230 (incooperation with the processor 216 executing code of the VP logic 228)in processing reconstructed pictures for display and/or output.

The demux 204 is coupled to a bus 205 and to a media engine 206. Themedia engine 206 includes, in one embodiment, decoding logic having oneor more of a respective audio decoder 208 and video decoder 210. Themedia engine 206 is further coupled to the bus 205 and to media memory212, the latter which, in one embodiment, includes one or morerespective buffers for temporarily storing compressed (compressedpicture buffer or bit buffer, not shown) and/or reconstructed pictures(decoded picture buffer or DPB 213). In some embodiments, one or more ofthe buffers of the media memory 212 may reside in other memory (e.g.,memory 222, explained below) or components.

The VSRP device 200 further includes additional components coupled tothe bus 205 (though shown as a single bus, one or more buses arecontemplated to be within the scope of the embodiments). For instance,the VSRP device 200 further includes a receiver 214 (e.g., infrared(IR), radio frequency (RF), etc.) to receive user input (e.g., viadirect-physical or wireless connection via a keyboard, remote control,voice activation, etc.) to convey a user's request or command (e.g., forprogram selection, trick mode manipulation such as fast forward, rewind,pause, channel change, one or more processors (one shown) 216 forcontrolling operations of the VSRP device 200, and a clock circuit 218comprising phase and/or frequency locked-loop circuitry to lock into asystem time clock (STC) from a program clock reference, or PCR, receivedin the bitstream to facilitate decoding and output operations. Althoughdescribed in the context of hardware circuitry, some embodiments of theclock circuit 218 may be configured as software (e.g., virtual clocks)or a combination of hardware and software. Further, in some embodiments,the clock circuit 218 is programmable.

The VSRP device 200 may further include a storage device 220 (andassociated control logic as well as one or more drivers in memory 222)to temporarily store buffered media content and/or more permanentlystore recorded media content. The storage device 220 may be coupled tothe bus 205 via an appropriate interface (not shown).

Memory 222 in the VSRP device 200 comprises volatile and/or non-volatilememory, and is configured to store executable instructions or codeassociated with an operating system (O/S) 224 and other applications,and one or more applications 226 (e.g., interactive programming guide(IPG), video-on-demand (VOD), personal video recording (PVR), WatchTV(associated with broadcast network TV), among other applications notshown such as pay-per-view, music, driver software, etc.).

Further included in one embodiment in memory 222 is video processing(VP) logic 228, which in one embodiment is configured in software. Insome embodiments, VP logic 228 may be configured in hardware, or acombination of hardware and software. The VP logic 228, in cooperationwith the processor 216, is responsible for interpreting assistanceinformation and providing the appropriate settings for a display andoutput system 230 of the VSRP device 200. In some embodiments,functionality of the VP logic 228 may reside in another component withinor external to memory 222 or be distributed among multiple components ofthe VSRP device 200 in some embodiments.

The VSRP device 200 is further configured with the display and outputlogic 230, as indicated above, which includes one or more output systems(e.g., configured as HDMI, DENC, or others) 233 to process the decodedpictures and provide for output or presentation (e.g., display) ondisplay device 140. Though shown conceptually in FIG. 2 as an entityseparate from the media engine 206, in some embodiments, one or more ofthe functionality of the display and output logic 230 may beincorporated in the media engine 206 (e.g., on a single chip) orelsewhere in some embodiments.

A communications port 234 (or ports) is (are) further included in theVSRP device 200 for receiving information from and transmittinginformation to other devices. For instance, the communication port 234may feature USB (Universal Serial Bus), Ethernet, IEEE-1394, serial,and/or parallel ports, etc. The VSRP device 200 may also include one ormore analog video input ports for receiving and/or transmitting analogvideo signals.

In one embodiment, a system component located in headend 111 orelsewhere in network 130 includes all or a portion of the processingcomponents in VSRP 200 to effect to modify a coded video signal byordering the base layer and enhancement layer packets of the coded videosignal.

VSRP device 200 may include other components not shown, includingdecryptors, samplers, digitizers (e.g., analog-to-digital converters),multiplexers, conditional access processor and/or application software,driver software, Internet browser, among others. Further, though the VPlogic 228 is illustrated as residing in memory 222, it should beunderstood that all or a portion of such logic 228 may be incorporatedin, or distributed among, the media engine 206, the display and outputsystem 230, or elsewhere. Similarly, in some embodiments, functionalityfor one or more of the components illustrated in, or described inassociation with, FIG. 2 may be combined with another component into asingle integrated component or device.

The VP system (e.g., encoder 111, splicer 112, decoding logic (e.g.,media engine 206), and/or display and output logic 230) may beimplemented in hardware, software, firmware, or a combination thereof.To the extent certain embodiments of the VP system or a portion thereofare implemented in software or firmware (e.g., including the VP logic228), executable instructions for performing one or more tasks of the VPsystem are stored in memory or any other suitable computer readablemedium and executed by a suitable instruction execution system. In thecontext of this document, a computer readable medium is an electronic,magnetic, optical, or other physical device or means that can contain orstore a computer program for use by or in connection with a computerrelated system or method.

To the extent certain embodiments of the VP system or portions thereofare implemented in hardware, the VP system may be implemented with anyor a combination of the following technologies: a discreet logiccircuit(s) having logic gates for implementing logic functions upon datasignals, an application specific integrated circuit (ASIC) havingappropriate combinational logic gates, programmable hardware such as aprogrammable gate array(s) (PGA), a field programmable gate array(FPGA), etc.

Having addressed certain embodiments of VP systems that decode the codedpictures of a bitstream, attention is directed to the use of theassistance information (or a separate and distinct piece of assistanceinformation in some embodiments) to assist the affecting of trick modefunctionality. An output clock (e.g., a clock residing in the clockingcircuit 218 or elsewhere) residing in the VSRP device 200 drives theoutput of reconstructed pictures (e.g., with an output system 233configured as HDMI or a DENC or other known output systems). The displayand output logic 230 may operate in one of plural modes. In one mode,often referred to as passthrough mode, the VSRP device 200 behavesintelligently, providing an output picture format corresponding to thepicture format determined upon the acquisition or start of a videoservice (such as upon a channel change) in union with the formatcapabilities of the display device 140 and user preferences. In a fixedmode (or also referred to herein as a non-passthrough mode), the outputpicture format is fixed by user input or automatically (e.g., withoutuser input) based on what the display device 140 supports (e.g., basedon interrogation by the set-top box of display device picture formatcapabilities).

In one embodiment, a system component such as the splicer 112 and/orencoder 111 deliver assistance information for reception and processingby the display and output logic 230, the assistance informationconveying to the display and output logic 230 information to affectcertain behavior to provide the requested trick mode. The assistanceinformation may pertain to picture interdependencies related bysuccessive tier numbers output of the decoded pictures. In someembodiments, a part of the assistance information may be providedaccording to a different mechanism or via a different channel or medium.

FIG. 3 is a flowchart illustrating a method 300 for modifying andproviding a coded video signal in a transport stream according toembodiments of the present disclosure. As shown in FIG. 3, method 300may start at stage 305 and proceed to stage 310. At stage 310, aninitial or first packet of an ith picture in a base layer of a codedvideo signal in a transport stream may be identified. Method 300 maythen proceed to stage 315. At stage 315, an initial or first packet ofan ith picture in an enhancement layer of the transport stream may beidentified. Next, method 300 may proceed to stage 320 where packets inthe transport stream may be reordered such that the initial packet ofthe ith picture in the enhancement layer occurs after the initial packetof the ith picture in the base layer.

Method 300 may then proceed to stage 325. At stage 325, a first orinitial packet of the (i+1)th picture in the base layer of the transportstream may be identified. Method may then proceed to stage 330, where afirst or initial packet of the (i+1)th picture in the enhancement layerof the transport stream may be identified. A last packet of the ithpicture in the enhancement layer may be identified as the packetimmediately prior to the initial packet of the (i+1)th picture in theenhancement layer. Next, method 300 may proceed to stage 335. At stage335, packets in the transport stream may be reordered such that the lastpacket of the ith picture in the enhancement layer occurs before theinitial packet of the (i+1)th picture in the base layer.

In one embodiment, method 300 may proceed to stage 340 where a minimumamount of delay or time may be provided between the initial packet ofthe ith picture in the enhancement layer and the initial packet of theith picture in the base layer is equal to or greater than a duration ofa transport stream packet at a piece-wise constant bit-rate applicableto a initial packet of the base layer. In some embodiment, the minimumtime may be more than the duration of one TS packet. For example, theminimum time may be a predetermined minimum number of TS packets, suchas a three TS packet duration.

In one embodiment, method 300 may proceed to stage 345 where a minimumtime between the last packet of the ith picture in the enhancement layerand the initial packet of the (i+1)th picture in the base layer is equalto or greater than a duration of a transport stream packet at apiece-wise constant bit-rate applicable to a last packet of theenhancement layer. In some embodiment, the minimum time may be more thanthe duration of one TS packet. For example, the minimum time may be apredetermined minimum number of TS packets, such as a three TS packetduration.

Where one or more generating stages are in conflict, a priority may beassociated with each stage, indicating which should take precedence. Twostages may be given the same priority, in which case, the placement usedmay be the average between the two indicated locations. In someembodiments, more complex algorithms than averaging may be used. Theconflict may result in the presence of very low bitrate transmissions.

Next, method 300 may proceed to stage 350 where the modified coded videosignal in a transport stream may be provided or transmitted across anetwork to a video processing device, such as VSRP device 200. In someembodiments of the present disclosure, the coded video signal istransmitted to a first type of VSRP device 200 and a second type of VSRPdevice 200. The first type of VSRP device 200 corresponds to asingle-PID-video processing device and the second type of VSRP device200 corresponds to a multi-PID-video-compatible processing device. Thefirst type of VSRP device 200 is capable of only processing the baselayer of the coded video signal and the second type of VSRP device 200is capable of performing operations and processing the base layer andone or more enhancement layers of the coded video signal. Accordingly,after ordering of the base and enhancement layer packets in thetransport stream of the coded video signal, the modified transportstream is provided and one or more operations may be performed at thesingle PID video processing device, such trick mode operations and TVchannel changes that do not include enhancement layer packetscorresponding to a picture prior to the RAP picture where video decodingcommences. From stage 350, method 300 may then end at stage 355.

In some embodiments of the present disclosure, a presentation time stampof the ith picture of the base layer is substantially equal to apresentation time stamp of the ith picture in the enhancement layer.Similarly, a decoding time stamp of the ith picture of the base layer issubstantially equal to a decoding time stamp of the ith picture in theenhancement layer.

In further embodiments, a tier value corresponding to the ith picture inthe enhancement layer is greater than or equal to the tier value of theith picture in the base layer. This could simplify coded picture bufferoperations allowing ordering to happen at the coded picture buffer levelrather than the decoded buffer level.

FIG. 4 is a flowchart illustrating a method 400 for processing a videostream according to embodiments of the present disclosure. As shown inFIG. 4, method 400 may start at stage 405 and proceed to stage 410. Atstage 410, packets may be ordered within a transport stream comprising abase layer and one or more enhancement layers. The packets may beordered such that a first or initial packet of an ith picture in a firstenhancement layer of the one or more enhancement layers may be orderedafter a first or initial packet of an ith picture in the base layer. Thepackets may be further ordered such that a last packet of the ithpicture in the first enhancement layer may be ordered before a first orinitial packet of an (i+1)th picture of the base layer.

From stage 410, method 400 may proceed to stage 415. At stage 415, theinitial packet of the ith picture in the first enhancement layer and thefirst or initial packet of the ith picture in the base layer may beordered such that the time between the first or initial packet of theith picture in the first enhancement layer and the initial packet of theith picture in the base layer may be at a minimum, a duration of atransport stream packet at a constant bit rate applicable to an initialpacket of the base layer.

Method 400 may then proceed from stage 415 to stage 420. At stage 420,the last packet of the ith picture in the first enhancement layer andthe initial packet of the (i+1)th picture in the base layer may beordered such that the time between the last packet of the ith picture inthe first enhancement layer and the initial packet of the (i+1)thpicture in the base layer may be at a minimum, a duration of a transportstream packet at a constant bit rate applicable to a last packet of thefirst enhancement layer. In some embodiments of the present disclosurepackets may be ordered at a network device located on a network betweenan encoder and the video processing device. From stage 420, method 400may then end at stage 425.

Any process descriptions or blocks in flow charts or flow diagramsshould be understood as representing modules, segments, or portions ofcode which include one or more executable instructions for implementingspecific logical functions or steps in the process, and alternateimplementations are included within the scope of the present disclosurein which functions may be executed out of order from that shown ordiscussed, including substantially concurrently or in reverse order,depending on the functionality involved. In some embodiments, steps ofprocesses identified in FIGS. 3 and 4 using separate boxes can becombined. Further, the various steps in the flow diagrams illustrated inconjunction with the present disclosure are not limited to thearchitectures described above in association with the description forthe flow diagram (as implemented in or by a particular module or logic)nor are the steps limited to the example embodiments described in thespecification and associated with the figures of the present disclosure.In some embodiments, one or more steps may be added to the methodsdescribed in FIGS. 3 and 4 either in the beginning, end, and/or asintervening steps, and that in some embodiments, fewer steps may beimplemented.

It should be emphasized that the above-described embodiments of thepresent disclosure are merely possible examples of implementations,merely set forth for a clear understanding of the principles of the VPsystems and methods. Many variations and modifications may be made tothe above-described embodiment(s) without departing substantially fromthe spirit and principles of the disclosure. Although all suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and protected by the following claims, thefollowing claims are not necessarily limited to the particularembodiments set out in the description.

We claim:
 1. An apparatus comprising: a memory; and one or moreprocessors configured to execute instructions stored in the memory, theinstructions comprising: identifying packets of a first bitstream in atransport stream, such first bitstream corresponding to a base layer;identifying packets of a second bitstream in the transport stream, suchsecond bitstream corresponding to an enhancement layer; identifying aninitial packet corresponding to an ith picture in the first bitstream;identifying an initial packet corresponding to the ith picture in thesecond bitstream; and reordering packets in the transport stream suchthat the initial packet corresponding to the ith picture in the secondbitstream occurs after the initial packet corresponding to the ithpicture in the first bitstream.
 2. The apparatus of claim 1, wherein theinstructions further comprise: identifying an initial packetcorresponding to the i+1th picture in the first bitstream; identifying alast packet corresponding to the ith picture in the second bitstream;and reordering packets in the transport stream such that the last packetof the ith picture in the second bitstream occurs before the initialpacket of the i+1th picture in the first bitstream.
 3. The apparatus ofclaim 1, wherein a presentation time stamp corresponding to the ithpicture in the first bitstream is substantially equal to a presentationtime stamp corresponding to the ith picture in the second bitstream. 4.The apparatus of claim 1, wherein a decoding time stamp corresponding tothe ith picture in the first bitstream is substantially equal to adecoding time stamp corresponding to the ith picture in the secondbitstream.
 5. The apparatus of claim 1, wherein the ith+1 picture in thefirst bitstream corresponds to the next picture in decode order afterthe the ith picture in the first bitstream.
 6. The apparatus of claim 1,wherein the ith+1 picture in the second bitstream corresponds to thenext picture in decode order after the the ith picture in the secondbitstream.
 7. The apparatus of claim 1, wherein identifying packets of afirst bitstream in a transport stream is responsive to determining apacket identifier (“PID”) value corresponding to the first bitstream. 8.A method, comprising: identifying packets of a first bitstream in atransport stream, such first bitstream corresponding to a base layer;identifying packets of a second bitstream in the transport stream, suchsecond bitstream corresponding to an enhancement layer; identifying aninitial packet corresponding to an ith picture in the first bitstream;identifying an initial packet corresponding to the ith picture in thesecond bitstream; and reordering packets in the transport stream suchthat the initial packet corresponding to the ith picture in the secondbitstream occurs after the initial packet corresponding to the ithpicture in the first bitstream.
 9. The method of claim 8, wherein theinstructions further comprise: identifying an initial packetcorresponding to the i+1th picture in the first bitstream; identifying alast packet corresponding to the ith picture in the second bitstream;and reordering packets in the transport stream such that the last packetof the ith picture in the second bitstream occurs before the initialpacket of the i+1th picture in the first bitstream.
 10. The method ofclaim 8, wherein a presentation time stamp corresponding to the ithpicture in the first bitstream is substantially equal to a presentationtime stamp corresponding to the ith picture in the second bitstream. 11.The method of claim 8, wherein a decoding time stamp corresponding tothe ith picture in the first bitstream is substantially equal to adecoding time stamp corresponding to the ith picture in the secondbitstream.
 12. The method of claim 8, wherein the ith+1 picture in thefirst bitstream corresponds to the next picture in decode order afterthe the ith picture in the first bitstream.
 13. The method of claim 8,wherein the ith+1 picture in the second bitstream corresponds to thenext picture in decode order after the the ith picture in the secondbitstream.
 14. The method of claim 8, wherein identifying packets of afirst bitstream in a transport stream is responsive to determining apacket identifier (“PID”) value corresponding to the first bitstream.15. A method of encoding a sequence of uncompressed pictures into acoded video signal in transport stream (“TS”) bitstream that includes afirst bitstream and a second bitstream, comprising: receiving a sequenceof uncompressed pictures including a first picture; and processing thefirst picture into a coded picture comprising a first sequence ofpackets in the first bitstream and a second sequence of packets in thesecond bitstream, such that the initial packet of first picture in thesecond bitstream is after the initial packet of first picture in thefirst bitstream.
 16. The method of claim 15, further comprising:processing a second picture of the sequence of uncompressed picturesinto a second coded picture comprising a third sequence of packets inthe first bitstream and a fourth sequence of packets in the secondbitstream, such that the last packet of the first picture of the secondbitstream is after the initial packet of the second picture in the firstbitstream.
 17. The method of claim 15, wherein the third sequence ofpackets is immediately after the first sequence of packets in the firstbitstream.
 18. The method of claim 15, wherein the fourth sequence ofpackets is immediately after the second sequence of packets in thesecond bitstream.
 19. The method of claim 15, further comprising:processing a second picture of the sequence of uncompressed picturesinto a second coded picture comprising a third sequence of packets inthe first bitstream and a fourth sequence of packets in the secondbitstream, wherein the second picture corresponds to a RAP picture andthe first picture corresponds to a picture immediately prior to the RAPpicture.
 20. The method of claim 15, further comprising providing apresentation time stamp for the first picture in the first bitstreamthat is substantially equal to a presentation time stamp for the firstpicture in the second bitstream.
 21. The method of claim 15, furthercomprising: processing a second picture of the sequence of uncompressedpictures into a second coded picture comprising a third sequence ofpackets in the first bitstream and a fourth sequence of packets in thesecond bitstream; and providing a presentation time stamp for the secondpicture in the first bitstream that is substantially equal to apresentation time stamp for the second picture in the second bitstream.22. The method of claim 15, further comprising providing a decoding timestamp for the first picture in the first bitstream that is substantiallyequal to a decoding time stamp for the first picture in the secondbitstream.
 23. The method of claim 15, further comprising: processing asecond picture of the sequence of uncompressed pictures into a secondcoded picture comprising a third sequence of packets in the firstbitstream and a fourth sequence of packets in the second bitstream; andproviding a decoding time stamp for the second picture in the firstbitstream that is substantially equal to a decoding time stamp for thesecond picture in the second bitstream.